Since X-ray is multicolor spectroscopy ray, in Computed Tomography (CT) medical imaging technology, X-ray with higher energy has lower attenuation than the X-ray with lower energy. With the projection thickness of X-ray increasing, X-ray with higher energy become more, causing beam hardening phenomenon, thus the beam hardening artifact exists in the reconstructed image.
At present, the beam hardening artifact may be reduced by some correction methods which are not ideal for the beam hardening artifact caused by a bone tissue.
For example, in prior art, the original image is obtained by reconstructing the original projection data, a bone tissue image is extracted from the reconstructed original image, the extracted bone tissue image is projected, and the beam hardening artifact is corrected based on the projection data of the bone tissue image.
However, due to beam hardening, the obtained original projection data itself may be not accurate, so that neither the extracted bone tissue image nor the projection data of the bone tissue image is accurate, thus it is difficult to obtain more accurate correction data.
Both FIG. 12a and FIG. 12b are images obtained after performing the beam hardening correction on human brain image in prior art. As shown in FIG. 12a and FIG. 12b, after the image correction using the currently existing correction method, the beam hardening artifact is less, but the point where the bone tissue around the brain connects with the soft tissue is still obscure.